The present invention relates to a mobile equipment hitch which can be converted for engagement with either a releasable fifth wheel of a semitrailer truck or other highway vehicle or a tow bar coupling of an agricultural tractor, bulldozer or other field vehicle. The convertible hitch of the present invention permits mobile equipment to be towed by means of a conventional tow bar when in use in the field, but to be towed by means of a conventional, releasable fifth wheel when being transported down the highway between job sites.
Mobile equipment, such as used in agriculture, construction, and the like, is typically towed in the field by an agricultural tractor, bulldozer or similar self-propelled field vehicle by means of a conventional tow bar and tow bar coupling. This conventional form of towing in the field is the simplest, most efficient and most effective form of towing under conditions typically encountered in the field, wherein the quality and grade of the terrain vary significantly. An example of such mobile equipment is a mobile machine for uprooting vegetation from the ground, disclosed in U.S. Pat. No. 4,602,686 (fully incorporated herein by reference) and depicted in FIG. 1 herein. As seen in FIG. 1, the mobile equipment 1 includes a source of power 2 for operating the vegetation uprooting machinery, but does not include an engine or other source of power for propelling itself. Accordingly, the mobile equipment is provided with a tow bar member 3 which is removably attachable to a tow bar coupling on an agricultural tractor, bulldozer or the like (not shown) in a conventional manner. In the particular mobile equipment depicted in FIG. 1, and disclosed in U.S. Pat. No. 4,602,686, the tow bar member 3 has a pair of wheels 4 mounted thereon, and the tow bar member 3 is attached to a gooseneck 5 on the mobile equipment. A ball joint, knuckle joint or other flexible connection (not shown) is typically provided between tow bar member 3 and gooseneck 5 to provide universal flexibility between the field vehicle and the mobile equipment.
Although the conventional tow bar is satisfactory for towing mobile equipment in the field during use, it has been found unacceptable for towing the mobile equipment on the highway between job sites. In particular, the tow bar form of towing is unstable at highway speeds, especially in view of the ball joint which is typically provided between the tow bar and the gooseneck or other portion of the mobile equipment. Additionally, the conventional pin connection between the tow bar member and the tow bar coupling is also not considered sufficiently safe at highway speeds. Accordingly, a need has long existed for a hitch which can be simply, efficiently and effectively used for towing mobile equipment in the field, and at the same time be safely used for towing the mobile equipment down the highway between job sites.
Efforts were made by the present inventor to modify the mobile equipment to include a hitch such as found on conventional semitrailers which would be engageable with a releasable fifth wheel of a semitrailer truck or other highway vehicle. In this way, it was understood that the mobile equipment could be safely towed down the highway. However, there remained the problem of how to tow the mobile equipment in the field. The present invention attempted to resolve this problem by mounting a conventional, releasable fifth wheel on the agricultural tractor, bulldozer or other field vehicle to be utilized for towing the mobile equipment in the field. However, this approach suffered from a number of disadvantages. First, it was difficult to modify a conventional field vehicle to include a releasable fifth wheel, and it was in fact impossible with regard to certain field vehicles due to their construction. Second, each field vehicle to be utilized was required to be modified before it could be utilized to tow the mobile equipment in the field. Third, it was found that the conventional, releasable fifth wheel was not sufficiently durable to withstand use over rough terrains typically found in the field, and it was therefore necessary to replace the releasable fifth wheel after a very short period of use.
Thus, despite the present inventor's early efforts, there remained a need for a hitch which would overcome the foregoing disadvantages, while at the same time permitting simple, efficient, effective and safe towing of mobile equipment both in the field and on the highway.